nrvo shouldn't touch bycopy object[backport:1.2] (#19385)

fix nim-lang#19342

tests/objects/t19342.nim

@@ -0,0 +1,18 @@
+discard """
+  targets: "c cpp"
+"""
+
+{.compile: "m19342.c".}
+
+# bug #19342
+type
+  Node* {.bycopy.} = object
+    data: array[25, cint]
+
+proc myproc(name: cint): Node {.importc: "hello", cdecl.}
+
+proc parse =
+  let node = myproc(10)
+  doAssert node.data[0] == 999
+
+parse()